The wire feeding means of a conventional welding apparatus for a consumable electrode is arranged such that after a switching device is closed, both ends of a motor coil are short-circuited or connected through resistance so as to speedily lower the counter electromotive voltage generated by a motor portion and reduce the rotational energy of the motor portion, thereby applying a brake (e.g., refer to patent document 1).
Referring to FIG. 4, a description will be given of this conventional configuration.
FIG. 4 shows the configuration of the welding wire feeding means of a conventional welding apparatus for a consumable electrode. Reference numeral 101 denotes a welding power supply; 102, a feeding means for feeding a welding wire by a drive current from the welding power supply 101; 103, a motor disposed inside the feeding means 102; 104, a motor control means disposed inside the welding power supply 101; 104a, a switching device for controlling the drive current of the motor 103 by effecting the opening and closing operation by means of the motor control means 104; 105, a motor stop means constituted by a switching device which is opened when driving the motor 103 and is closed when stopping the motor 103 by the motor control means 104; and 106, a motor driving power supply. Reference numerals 107a and 107b denote control lines for connecting the welding power supply 101 and the feeding means 102.
In addition, the motor driving power supply 106 forms a circuit by series connection of the motor driving power supply 106, the switching device 104a, and the motor 103.
In addition, the motor stop means 105 is connected to a node between the switching device 104a and the motor 103 and to the other end of the motor 103, i.e., to both ends of the motor 105.
In addition, the connection is provided such that a control signal of the motor control means 104 is inputted to an input end of an open/close control signal of the switching device 104a, and such that a control signal is inputted to an input end of an open/close control signal of the switching device of the motor stop means 105.
As for its operation, when a motor drive signal from the motor control means 104 to the switching device 104a becomes OFF, the switching device 104a is set in an open state.
Meanwhile, the motor control means 104 outputs a signal for closing the circuit to the motor stop means 105 so as to speedily lower the counter electromotive voltage generated by the motor 103 and reduce the rotational energy of the motor 103, thereby applying a brake.
Patent document 1: JP-A-2002-283052